1. Field of the Invention
The present invention relates to a mobile station, a radio communication system, a base station switching control method, a program, and a recording medium.
2. Description of the Related Art
Recent developments of communication of multimedia information involve expansion of communication capacities in digital mobile communication. This increases loads placed on the CPUs of mobile stations and creates a demand for further improvements in reliability of communication channel qualities.
International application published under the PCT WO99/34627 (Date of publication: Jul. 8, 1999) discloses a technique which restricts handover and changes handover threshold according to handover history and communication quality. This technique improves the quality of communication by lowering the frequency of unnecessary handovers. This technique also improves the quality of communication by enhancing the detection accuracy of base station switching timing.
Japanese patent laid-open publication JP 2001-078242 A (Date of publication: Mar. 23, 2001) also discloses a technique for improving the quality of communication, in which the quality of communication through communication channels is monitored and a switch of base stations is facilitated when the signal from the connected base station deteriorates. This technique is also capable of improving the quality of communication by enhancing the detection accuracy of base station switching timing.
Japanese patent laid-open publication JP 2002-010313 A (Date of publication: Jan. 11, 2002) concentrates on the fact that fading variations become more intense depending on the movement speed and also increases the possibility of selecting a most suitable base station by adopting a longer measuring time and a larger internal threshold when the movement speed is at high levels. A technique is also disclosed which adopts a shorter measuring time and a smaller internal threshold when the movement speed is at low levels. This technique searches for candidate base stations to which a switch is to be made.
Japanese patent laid-open publication JP 2002-204181 (Date of publication: Jul. 19, 2002) discloses a technique that considers the positional relation between a mobile station and a base station communicating with each other. When a mobile station and a base station are positioned close enough to perform stable communication, unnecessary operations of detecting multipaths from other base stations are prevented to reduce dissipated power consumption. This technique realizes reduction of power consumption which is a problem to be solved when using RAKE receivers.
However, there exist no techniques invented with a view to enhancing the reliability of communication channels by reducing packet loss caused during switching of base stations and by reducing burdens on the CPUs of mobile stations by controlling the switching of base stations.